Effect of avoiding cardiopulmonary bypass in non-elective coronary artery bypass surgery: a propensity score analysis

Objective: Non-elective coronary artery surgery (emergent/salvage or urgent) carries an increased risk in most risk-stratification models. Off-pump coronary surgery is increasingly used in non-elective cases. We aimed to investigate the effect of avoiding cardiopulmonary bypass on outcomes following non-elective coronary surgery. Methods: Of the 3771 consecutive coronary artery bypass procedures performed by five surgeons between April 1997 and March 2002, 828 (22%) were non-elective and 417 (50.4%) of these patients had off-pump surgery. Multivariate logistic regression was used to assess the effect of off-pump on in-hospital outcomes, while adjusting for treatment selection bias. Treatment selection bias was controlled for by constructing a propensity score from core patient characteristics, which was the probability of avoiding cardiopulmonary bypass. The C statistic for this model was 0.8. Results: Off-pump patients were more likely to be hypertensive, stable, had less extensive disease and better left ventricular function. The left internal mammary artery was used in 91.8% (n = 383) of off-pump patients compared to 79.3% (n = 326) of on-pump cases (P < 0.001). After adjusting for the propensity score, no difference in in-hospital mortality was observed between off-pump and on-pump (adjusted odds ratio (OR) 0.83 (95% confidence intervals (CI) 0.36-1.93); P = 0.667). Off-pump patients were less likely to require intra-aortic balloon pump support (adjusted OR 0.44 (95% CI 0.21-0.96); P = 0.039), less likely to have renal failure (adjusted OR 0.44 (95% CI 0.22-0.90); P = 0.025), and have shorter lengths of stay (adjusted OR 0.51 (95% CI 0.37-0.70); P < 0.001). Other morbidity outcomes were similar in both groups. Conclusions: In this experience, off-pump coronary surgery in non-elective patients is safe with acceptable results. Non-elective off-pump patients have a significantly reduced incidence of renal failure, and shorter post-operative stays compared to on-pump coronary artery bypass surgery. (C) 2003 Elsevier Science B.V. All rights reserved.